Many neurological disorders are caused by the absence or failure of neural impulses, which result in the loss of control of certain body functions. In many cases, electrical stimulation can be used to restore the impaired functions. Considerable progress has been made in this area in recent years and efforts to microminiaturize the stimulator and electrodes are underway. One of the components that limits the size and performance of the injectable microstimulators under development is a hybrid charge storage capacitor. The overall goal of the proposed program is to adapt the Giner, Inc. Electrochemical Capacitor technology to this application and develop a charge storage capacitor with improved performance and/or reduced size. Electrochemical capacitors store energy by utilizing double layer and surface redox processes. Giner, Inc. capacitor technology is based on high-area RuOx as active material and a polymeric perfluorosulfonate solid ionomer as the electrolyte and membrane separator. The Phase I program clearly showed the feasibility of adapting and miniaturizing the Giner, Inc. electrochemical solid ionomer capacitor for use in a microstimulator. The proposed Phase II work extends the investigation to the utilization of higher-energy-density electrodes and lower ionic resistance ionomers to further reduce the dimensions of the microcapacitor elements, development of fabrication and sealing techniques suitable for such small dimensions and assembly/test of a fully packaged 10-cell microcapacitor in a hermetically sealed microstimulator.